2004: Vinny Testaverde, Dallas Cowboys
It shouldn’t be that much of a surprise that the worst quarterback of the 2004 NFL season also happened to be seven years older than any other starting quarterback in the league. Playing for his 5th team in 17 seasons at that point, Vinny Testaverde had one of his worst seasons as a starting quarterback since he had left the miserable situation in Tampa Bay (the team that drafted him).
He tied for the most interceptions thrown by any quarterback that year (20), and won only five of the 15 games he started for Dallas Cowboys. At 41 years old that year, it was his last season as a starting quarterback in the NFL.